Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual posição teve 7 aparições na equipe principal?
 ###Tabelas: CREATE TABLE doubles:_13_9_titles_4_runners-up (doubles:_13_9_titles_4_runners-up_id AUTO_INCREMENT PRIMARY KEY, Outcome VARCHAR, Year VARCHAR, Championship VARCHAR, Surface VARCHAR, Partner VARCHAR, Opponents VARCHAR, Score VARCHAR) CREATE TABLE semi-final_2 (semi-final_2_id AUTO_INCREMENT PRIMARY KEY, Draw INT, Artist VARCHAR, Song VARCHAR, Jury votes INT, Televotes INT, Total votes INT, Result VARCHAR) CREATE TABLE top_10_games_of_400_or_more_yards_by_category (top_10_games_of_400_or_more_yards_by_category_id AUTO_INCREMENT PRIMARY KEY, Rank VARCHAR, Rating VARCHAR, Completion Percentage VARCHAR, Touchdown Percentage VARCHAR, Yards Per Attempt VARCHAR, Total Yards VARCHAR) CREATE TABLE 2010s (2010s_id AUTO_INCREMENT PRIMARY KEY, Player VARCHAR, Position VARCHAR, First-Team Appearances VARCHAR, First-Team Goals VARCHAR, Current Club VARCHAR) CREATE TABLE college_career_statistics (college_career_statistics_id AUTO_INCREMENT PRIMARY KEY, Season VARCHAR, GP/MP VARCHAR, Kills INT, K/Game INT, Errors INT, Total Attempts INT, Percentage INT, Assists INT, Service Aces INT, Digs INT, Solo Blocks INT, Block Assists INT, Total Blocks INT, Points INT)  
SELECT Position FROM 2010s WHERE First-Team Appearances = 7